High entropy catalysts in electrolytic water splitting: A review from properties to applications

• Based on the mechanism of water electrolysis, the design requirements of high efficiency catalyst are proposed. • The four core effects of high entropy materials on HER and OER. • The application of high entropy catalyst in water electrolysis is analyzed experimentally and theoretically. • The prospect of high entropy materials to design membrane electrode is proposed innovatively. High entropy catalysts (HECs), with their unique microstructures, flexible design of elemental composition and excellent catalytic activity, have entered the field of electrocatalysis as promising catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER). First, this review outlines the fundamental mechanisms of HER and OER as well as the requirements for the corresponding catalysts. Second, four compelling effects of (HECs) – namely, the high-entropy effect, lattice distortion effect, sluggish diffusion and cocktail effect – are introduced in a systematic manner, and their impact on the catalytic electrolytic water splitting process is analysed. Then, the application of catalysts in water splitting is analyzed from both theoretical and experimental perspectives, in combination with the four major effects of HECs. Finally, the challenges and opportunities of HECs are analyzed in detail. With the deepening of scientific research and the continuous improvement of technical means, it is believed that HECs will have broader application prospects in the future and make important contributions to the development of energy, environment, and other fields.